The present invention relates to a system for measuring ionizing radiation, in particular for radiometric level measurements, with a scintillator incorporating a first assembly of at least two rod-shaped scintillator elements, which can be optically coupled to one another via their opposed face ends, a second assembly of interconnectable sheath elements wherein said first assembly of scintillator elements is coaxially enclosed by said second assembly of interconnectable sheath elements, and at least two face-end window elements.
Radiometric level measurements are performed primarily by means of detectors with long organic scintillators, which are coupled at one end to a photomultiplier. The sensitive length of such detectors is limited by the manufacturer of the scintillator material and by practical aspects (production, transportation, assembly) to approximately 2 m. If measurement areas >2 m are required in radiometric level measurements, multiple identical detectors are commonly distributed over the measurement area and are switched in series. The counts from the individual detectors are added together and the fill level is determined based on the calibration. One shortcoming of this approach lies in its high costs, as each detector must be provided with its own amplifier electronic units and evaluation units (e.g. photomultiplier, amplifier circuits, digital component, bus connection). Moreover, the detectors must be connected individually to supply and signal lines.
In the German utility model DE 201 03 881 U1, a rod-type detector is described, in which the sensitive part consists of a plurality of scintillator rods that are placed on top of each other and are optically coupled to each other, and are read out at one end by a single photomultiplier. The advantage of such a detector lies, on the one hand, in the noticeable cost reduction by economies in measuring electronics and wiring and, on the other hand, in a lesser likelihood of a breakdown of the entire measuring system (FMEA number) due to a reduced number of components. In this manner large measurement areas can be covered while at the same time providing for a high degree of sensitivity and linearity. However, the scintillator rods can only be connected once they are on-site. The individual scintillator rods must be aligned relative to each other on-site, optically coupled and placed into a protecting tube. This method is problematic in light of the susceptibility of the scintillator material to soiling and mechanical damage and in light of the oftentimes difficult conditions on-site.